Gravity-operated mercury switch with conically shaped reservoir

ABSTRACT

A gravity-operated mercury switch having a mercury reservoir with a cone-shaped base, the reservoir communicating by way of a throatlike aperture with the apex of a conical switching surface contained in the switch body. The throatlike aperture comprises a passage for the mercury and a plurality of vents dimensioned so as to allow free flow of gas along the vents but not to allow entry of mercury into the vents. The conical switching surface may be of irregular form having angles varying from 15* to 90*, may have more than one slope and may be stepped.

United States Patent Inventor Leslie Chapman Yorkshire, England Appl. No; 888,749

Filed Dec. 29, 1969 Patented Dec. 14, 1971 Assignee Lelio Development & Products Limited Leeds, Yorkshire, England GRAVITY-OPERATED MERCURY SWITCH WITH CONICALLY SHAPED RESERVOIR 5 Claims, 19 Drawing Figs.

[1.8. CI. 200/223, 200/6l.47, ZOO/61.52, 200/189, 200/l 9l Int. Cl .1. .H0 lh 29/00, HOlh 29/20, HOlh 29/22 Field of Search 200/152,

[56] References Cited UNITED STATES PATENTS 2,145,543 1/1939 Gross ZOO/61.47 X 3,034,097 5/1962 English et al.. 200/6 1 .47 X

Primary Examiner-Herman J. Hohauser Attorney-Abraham A. Saffitz SHEET 3 [IF 6 PATENTED DEC14|97| m weA/roe LESLIE CHAPMAN f/ulw l% ATTORNEY PATENTED ummsm 31527352 SHEET M M 6 PATENTED nan] 4m $621,962

SHEET 5 BF 6 LESLIE CHAP MW 6% ATTORNEY PATENTEU DEB] 4|97| $527,952 sum 6 or s Phi/7 ATTORNE GRAVITY-OPERA'IEDMERQURY SWlTCI-lWI'll-l' CONICALLY SHAPEDRESERVOIR tion of mercury switch-which has operating'surfaces-of varying. I

in the form, proportions, and details of construction, within the scope ofthe claims may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention. In the drawings: FIG. 1 is an exploded part sectional view of the basic form of mercury switch;

FIG. 2 isan enlarged detailview of the body of a switch; FIGS. 3' to 7 are fragmentary diagrammatic views of the basic switch body showing, alternative sizes and locations of the mercury reservoir;

FIGS. 8 to I2 show diagrammatically modified forms of a compensated switch body in which variations of the switching angle throughout 360 in the horizontal plane are provided;

FIG. 13 shows a sectional elevation of a sequential type switch; I

FIGS. 14 to 17 show modified forms of switch body constituting a combined compensated and sequential switch;

FIG. 18 shows a method of varying the sequence of operation of the switch; I

FIG. 19 shows a suitable housing for a mercury switch and connecting pins.

In the accompany drawings which illustrate preferred embodiments of the invention, the basic switch is shown in FIGS. 1 and 2.

The operating surfaces l of the switch are basically conical in form, with an outlet bore .2 for the passage of the mercury, situated at the apex of the inverted cone.

Beneath this bore is an annular reservoir 3 designed to contain the mercury when the switch is at rest.

The reservoir is produced by means of the introduction and insertion of the "well-cone 12.

An insulating ring 5 separates a top cover plate 4 from the switch body 6, and the cover plate is secured to the switch body 6 by means of fixing screws 7 which are electrically insulated from the cover plate 4 by means of insulated bushes 8 and washers 9 or simply by Nylon fixing screws omitting the insulating bushes and washers.

The cover plate 4 insulating ring 5 and body 6 are efficiently sealed to prevent any leakage of mercury, by a suitable bonding cement. A terminal screw 4A is provided in the cover 4.

Apertures which constitute vents 10 in the form of slots, permit a freedom of flow of the mercury, by allowing the equilization of pressure in the upper chamber of the switch and the reservoir when the switch is tilted during its operational functioning. (See FIGS. 2 to 7).

The width of the said vents 10 is of such dimension as not to allow the mercury to flow into such slots, due to the high surface tension of the mercury itself.

Alternatively the vents 10 may be provided by holes of suitable diameter which would extend from the upper chamber of the switch to the reservoir 3. (See FIGS. 16 and 17).

The well-cone 12 may be bonded to the switch body 6 by a suitable bonding cement.

A suitable volume of: mercury is containedin the'reser-voir, whenthe switch isat rest. with its vertical centerline-at to, the horizontal plane.

The switching surface inzthe switch-body 6is basically conical'in form, but certainrequirements ofswitching, dictate that variations of the switching, angles may be demanded throughout the full 360 of the horizontal plane. This requirementis satisfactorily achieved, by the introduction'of a compensated. insert" which is afiixed to the conical surfaces. 1. of

the'switch body. (SeeFIGS. 81c 12 These inserts are referredtoas strumsfl' (anetymological innovation: being a: contraction of the geometrical term, FRUSTRUM" Commencing at A (FIG. 9) withan operating angle of 32 (see FIG. 8), then proceeding in a clockwise direction to Y and constantly varyingto an angle of 45, thencontinuingonwards to Bwhere the switch angle becomes 35, then onwards again toZ where the angle becomes 60 with the operatingangles constantly varying, the 360 in the horizontal plane. is completed on return to the commencing point at A with its angle of 32.

' While angles of 32 to 60 are referred to, angles of from 15 to 90 may be employed.

FIG. [3 shows asequential type switch.

Sequentialswitching isv arranged, by providing pairs of insulated contactor rings 14 at suitably placed intervals at the terminations of surfaces of the switch having desired angles of operation and these may be of any required number.

As shown, this feature is applied to a basic-type switch previously described, but it is to be noted, that the compensating feature may be applied to suit any contingency as may be so desired and as will be later described.

The basic type of sequential switch is shown in FIGS. 13 and 14 described as follows:

' The operating surfaces 1 of the switch, are basically conical in form, with an outlet bore 2 for the passage of the mercury, situated at the apex of the inverted cone.

Beneath this bore is an annular reservoir 3 designed to contain the mercury when the switch is at rest.

The reservoir 3 is produced by means of the introduction and insertion of the well-cone" 12.

An insulating ring 5 separates a top cover plate 4 from the switch body 6, the cover plate being secured by means of fixing screws 7, which'are electrically insulated from the cover plate 4 by means of insulated bushes 8 and washers 9, (or simply by Nylon fixing screws, omitting the insulating bushes and washers).

The cover plate 4 insulating ring 5 and body 6, are efficiently sealed to prevent any leakage of mercury, by a suitable bonding cement. 1

Vents may be provided as previously described in the form of slots or small diameter holes which will permit the freedom of the flow of the mercury, by allowing the equilization of pressure in the upper chamber of the switch and the reservoir when the switch is tilted during its operational functioning.

FIG. 14 shows a form of sequential switch wherein the contactor rings are mounted in insulating material MA.

A combined sequential and compensating switch is shown in FIGS. 15 and 16 the vents 10 being in the form of holes.

When a separate sensing switch is required the cover plate may be modified as shown in FIG. 18 which is of electrical insulating material and has separate contacts l8.

FIGS. 3 to 7 show different forms of outlet bore 2 i.e. different widths or different radii, both features which enable the rate of transfer of the mercury from the reservoir to the operating surface to be controlled.

The volume of the reservoir may be varied by either the size of the well-cone or its axial location relative to the outlet bore 2 and means may be provided where this distance may be adjustable.

The switch may be constructed of any suitable material consistent with enabling the mercury to complete electrical contacts. It will of course be understood that the switch will be provided with suitable electrical terminals or connections.

As shown in FIG. 19, the switch may be encased and provided with a plurality of pins to enable it to be plugged into an electric socket or circuit and thereby provide a quick means of effecting interchangability of switches.

While the switch has been described as a mercury" switch, any other suitable electrical conducting liquid such as an electrolite could be used as the switching medium.

I claim:

1. A gravity-operated mercury switch comprising in combination;

a switch body defining at least the upper part of a reservoir for the mercury, the base of said reservoir being of coneshaped form; g

a substantially conical switching surface contained in said switch body;

a top cover plate sealingly secured to said switch body;

said switch body formed with a restricted throatlike aperture between said reservoir and the apex of said conical switching surface;

said switch body further being formed with a plurality of vents extending through said switch body from said reservoir to said conical switching surface, said vents having a width which is less than that which will permit mercury to enter said vents due to the surface tension of the mercury and which is great enough for free flow of gas through said vents;

said vents and said throatlike aperture thus allowing flow of mercury from said reservoir to said conical switching surface and vice versa; and

terminals for said switch being provided for connecting to an electric circuit.

2. A gravity-operated switch comprising in combination a reservoir for the mercury, the base of said reservoir being of cone-shaped form, a substantially conical switching surface contained in the switch body, a restricted throatlike aperture between the said reservoir and the apex of the conical switching surface, the switch body being sealed by a top cover plate secured to the said switch body, said throatlike aperture having a plurality of vents in the form of apertures to facilitate and control the flow of mercury from the reservoir to the switch body and vice versa, suitable terminals being provided for connecting to an electric circuit said conical switching surface being of irregular conical form having varying angles from 15 to 3. A gravity-operated mercury switch according to claim 2 wherein the varying angles are provided by means of an insert located in the switch body.

4. A gravity-operated mercury switch comprising in combination a reservoir for the mercury, the base of said reservoir being of cone-shaped form, a substantially conical switching surface contained in the switch body, a restricted throatlike aperture between the said reservoir and the apex of the conical switching surface, the switch body being sealed by a top cover plate secured to the said switch body, said throatlike aperture having a plurality of vents in the form'of apertures to facilitate and control the flow of mercury from the reservoir to the switch body and vice versa, suitable terminals being provided for connecting to an electric circuit, said conical switching surfaces having more than one slope,

5. A gravity-operated mercury switch comprising in combination a reservoir for the mercury, the base of said reservoir being of cone-shaped form, a substantially conical switching surface contained in the switch body, a restricted throatlike aperture between the said reservoir. and the apex of the conical switching surface, the switch body being sealed by a top cover plate secured to the said switch body, said throatlike aperture having a plurality of vents in the form of apertures to facilitate the flow and control of mercury from the reservoir to the switch body and vice versa, suitable terminals being provided for connecting to an electric circuit, said conical switching surface being of irregular conical form having varying angles from l5 and 90, said conical switching surfaces having more than one slope and being also stepped.

i i I i l 

1. A gravity-operated mercury switch comprising in combination: a switch body defining at least the upper part of a reservoir for the mercury, the base of said reservoir being of coneshaped form; a substantially conical switching surface contained in said switch body; a top cover plate sealingly secured to said switch body; said switch body being formed with a restricted throatlike aperture between said reservoir and the apex of said conical switching surface; said switch body further being formed with a plurality of vents extending through said switch body from said reservoir to said conical switching surface, said vents having a width which is less than that which will permit mercury to enter said vents due to the surface tension of the mercury and which is great enough for free flow of gas through said vents; said vents and said throatlike aperture thus allowing flow of mercury from said reservoir to said conical switching surface and vice versa; and terminals for said switch being provided for connecting to an electric circuit.
 2. A gravity-operated mercury switch comprising in combination a reservoir for the mercury, the base of said reservoir being of cone-shaped form, a substantially conical switching surface contained in the switch body, a restricted throatlike aperture between the said reservoir and the apex of the conical switching surface, the switch body being sealed by a top cover plate secured to the said switch body, said throatlike aperture having a plurality of vents in the form of apertures to facilitate and control the flow of mercury from the reservoir to the switch body and vice versa, suitable terminals being provided for connecting to an electric circuit said conical switching surface being of irregular conical form having varying angles from 15* to 90* .
 3. A gravity-operated mercury switch according to claim 2 wherein the varying angles are provided by means of an insert located in the switch body.
 4. A gravity-operated mercury switch comprising in combination a reservoir for the mercury, the base of said reservoir being of cone-shaped form, a substantially conical switching surface contained in the switch body, a restricted throatlike aperture between the said reservoir and the apex of the conical switching surface, the switch body being sealed by a top cover plate secured to the said switch body, said throatlike aperture having a plurality of vents in the form of apertures to facilitate and control the flow of mercury from the reservoir to the switch body and vice versa, suitable terminals being provided for connectiNg to an electric circuit, said conical switching surfaces having more than one slope.
 5. A gravity-operated mercury switch comprising in combination a reservoir for the mercury, the base of said reservoir being of cone-shaped form, a substantially conical switching surface contained in the switch body, a restricted throatlike aperture between the said reservoir and the apex of the conical switching surface, the switch body being sealed by a top cover plate secured to the said switch body, said throatlike aperture having a plurality of vents in the form of apertures to facilitate the flow and control of mercury from the reservoir to the switch body and vice versa, suitable terminals being provided for connecting to an electric circuit, said conical switching surface being of irregular conical form having varying angles from 15* and 90* , said conical switching surfaces having more than one slope and being also stepped. 